The present application relates to a method of fabricating a semiconductor device, and more particularly, to a capacitor in a semiconductor device and a method of fabricating the same.
In general, a capacitor used for a memory cell includes a bottom electrode for storage, a dielectric layer, and a top electrode for a plate. In the fabrication of such a capacitor, high-k materials should be used for the dielectric layer to ensure a relatively greater capacitance within a limited area. However, the high-k materials have generally low band gap energy, thus causing a problem of degrading a leakage current property of the devices despite having a relatively high permittivity.
Attempts have been made to use ruthenium (Ru) having a high work function as the bottom or top electrode. However, since Ru has a relatively low cohesive reaction tendency with other materials, it poorly adheres to the substrate and thus a deposited-Ru film expands in a blister shape, regardless of the kinds of substrates to be target-adhered.
A technology has been proposed where RuO2 film with greater adhesive force and high work function is interposed below a Ru film, and is used as the bottom or top electrode. Although there are no particular adhesion problems in an initial deposition of the RuO2 film, the RuO2 film is reduced to decrease its thickness in subsequent processes, thereby causing a lifting of the RuO2 film and a formation of voids between the RuO2 film and the substrate.